So the other day I was driving on the highway at around 75mph and I come up to this bridge with a slight turn right after it. Maybe like a 3-5 degree direction difference. Basically, enough to make it so you couldn't keep the wheels straight with out going off the road. Anyway, this douche bag comes flying up like some Fast And Furious s//t in the middle of the lanes and flies in between me and this other car like the Saleen Mustang tried to do between the 2 tractor trailers in 2 Fast 2 Furious. It was crazy. Needless to say I had to hit the brakes pretty hard to avoid this guy from hitting me. Well the back end of the car started to kick back and forth and kinda slide and I thought I was going to slide in to the damn cement barrier.

Sooooooo I wanna know, will an after market rear sway bar help at all with keeping my back end from doing that kind of stuff or at least reduce it to a minimal?

The road was dry to btw.

 

I'm trying to picture this scenario you describe and can't help to wonder why you need to hit your brakes? Is he not coming up from behind you? Maybe swerve to give him room but why brake?

Heavy braking while turning with no ABS is not good. Try to avoid that.
If your car's brake bias is strong in the rear. I'd try to tune that out. Should be stronger in the front to avoid fishtailing.

I doubt a anti sway bar would solve your issues. Driver and braking first.

 

I kinda explained it wrong now that I really think about it. He tried to pass me in the middle of the road (I was in the left lane and there was a car in the right a head of me a little ways) and when he went to move over in front of me I had to brake because he was going really fast and there wasn't enough room to move over (cement wall) and if I hadn't braked he would have hit me.